Sohn Adapter and Pre mix
#76
Registered
This is what I use in the SOHN tank and as a premix. The Idematsu premix oil is a better deal, when bought in bulk, but the Lucas stuff is very convenient in my area.
All fuel maps do this. Fueling is done by load and RPM. At very low loads (foot off the gas), less fuel is injected, but the fuel system does not go completely lean. An AFR of around 16.0 is typical, however I have seen my 8 go as lean as 22.0 at no load (put it in neutral at high RPM and let it fall to idle). When engine braking, there is actually a decent amount of load at some RPM above 0, which means the AFR will typically be somewhere between 15.4 and 12.5, depending upon said load and RPM. An engine is an air pump that is always sucking in O2 as long as it is running. It needs matching fuel to keep it running, so it is always fueling to some degree when running.
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The point is, there is always fuel being supplied to a running engine. There are no zeros in the fuel map.
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The point is, there is always fuel being supplied to a running engine. There are no zeros in the fuel map.
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rx8rookiegirl (09-26-2021)
#77
Water Foul
I did get "good results" until my engine failed compression at 45K miles--or at least what I perceived as good results. This is akin to trying to prove a negative. I saw no signs of failure, until I saw signs of failure. That is not evidence that Lucas oil is of poor quality any more than it proves Lucas oil is of good quality, or that premix is worth it or not worth it. Did premix prolong the life of my engine? It is impossible to know.
My thinking on all this has changed quite a bit. I did ALL of the recommended things to preserve my engine (dozens of track hours notwithstanding), and it still failed in more than one mode. IMHO, these engines and/or their implementations suffer from flawed engineering, and any given engine will be a victim of its particular assembly. My engine was always going to fail, and there was nothing I could do (or amount of $$ I could spend) to prevent that, although the track hours do present a significant wild card. Still, that engine served my purposes for 7+ years, and I had a lot of fun with the car.
#78
Boosted Kiwi
iTrader: (2)
The RX-8 does use DFCO (Decel Fuel Cut-Off) in some circumstances, which is a toggle in the ECU, not a cell in the fuel tables of the ECU. This shuts down the injectors on no-load/decel when the engine is at full operating temperature and is in a throttle-off decel state, above 1,500RPM.
#79
Registered
This is obviously directed at me, but I'm not sure what your point is, other than to just be a contrarian.
I did get "good results" until my engine failed compression at 45K miles--or at least what I perceived as good results. This is akin to trying to prove a negative. I saw no signs of failure, until I saw signs of failure. That is not evidence that Lucas oil is of poor quality any more than it proves Lucas oil is of good quality, or that premix is worth it or not worth it. Did premix prolong the life of my engine? It is impossible to know.
My thinking on all this has changed quite a bit. I did ALL of the recommended things to preserve my engine (dozens of track hours notwithstanding), and it still failed in more than one mode. IMHO, these engines and/or their implementations suffer from flawed engineering, and any given engine will be a victim of its particular assembly. My engine was always going to fail, and there was nothing I could do (or amount of $$ I could spend) to prevent that, although the track hours do present a significant wild card. Still, that engine served my purposes for 7+ years, and I had a lot of fun with the car.
I did get "good results" until my engine failed compression at 45K miles--or at least what I perceived as good results. This is akin to trying to prove a negative. I saw no signs of failure, until I saw signs of failure. That is not evidence that Lucas oil is of poor quality any more than it proves Lucas oil is of good quality, or that premix is worth it or not worth it. Did premix prolong the life of my engine? It is impossible to know.
My thinking on all this has changed quite a bit. I did ALL of the recommended things to preserve my engine (dozens of track hours notwithstanding), and it still failed in more than one mode. IMHO, these engines and/or their implementations suffer from flawed engineering, and any given engine will be a victim of its particular assembly. My engine was always going to fail, and there was nothing I could do (or amount of $$ I could spend) to prevent that, although the track hours do present a significant wild card. Still, that engine served my purposes for 7+ years, and I had a lot of fun with the car.
or was it just sent back to mazda reman facility?
#82
Water Foul
I have tuned a handful of cars using 3 different ECUs, and I have never seen a data log with zero fuel supply, even with decel cut-off activated. They are normally limited to a max AFR of somewhere between 16 and 22. Obviously, I have nowhere near the experience of Brettus and furansu.
#83
///// Upscale Zoom-Zoom
That also wouldn't make any sense to have a point that has no fuel being supplied - the air pump (engine) requires fuel in all cases to balance the forces at work. I take that back -- the Saab Sonnett 2-stroke cut fuel off in certain decel situations; however it had oil injection to the combustion chamber.
#84
Registered
iTrader: (1)
I have tuned a handful of cars using 3 different ECUs, and I have never seen a data log with zero fuel supply, even with decel cut-off activated. They are normally limited to a max AFR of somewhere between 16 and 22. Obviously, I have nowhere near the experience of Brettus and furansu.
I never really thought to look at what it does on decel in detail... and it sort of doesn't matter, that's not the fun part of the engine regime, but the observation is curious. I've also not tuned RX8s.
The pulse width is tiny, I'm not sure it would do anything for tip-in response. But this is all to say I'm surprised, not that I disagree.
#86
Registered
Thank you for the correction.
#87
This is what I use in the SOHN tank and as a premix. The Idematsu premix oil is a better deal, when bought in bulk, but the Lucas stuff is very convenient in my area.
The RX-8 does use DFCO (Decel Fuel Cut-Off) in some circumstances, which is a toggle in the ECU, not a cell in the fuel tables of the ECU. This shuts down the injectors on no-load/decel when the engine is at full operating temperature and is in a throttle-off decel state, above 1,500RPM.
The RX-8 does use DFCO (Decel Fuel Cut-Off) in some circumstances, which is a toggle in the ECU, not a cell in the fuel tables of the ECU. This shuts down the injectors on no-load/decel when the engine is at full operating temperature and is in a throttle-off decel state, above 1,500RPM.
#88
Registered
Wait wait so y’all use Lucas oil in both the premix gas and the sohn tank? I’m super lost, I’m also reading it does nothing for you but then it does? Im very lost. On decel am I or am I not receiving enough oil to lubricate the engine? And if I install the sohn what’s the point in having premix still if I just use it as a daily? Sorry if this has been answered, I’m a new 8 owner.
I am a fan of a well-maintained factory oil injection system, using a SOHN kit to assure I can monitor oil consumption and use a 2stroke specific oil. My oil consumption from the SOHN reservoir is fairly consistent, increasing during track use since RPM’s are higher for longer. If you maintain and service the oil injections system like it is a wear item (test, clean and replace as-needed ever 50k miles), you’ll be alright.
Pre-mix is fine too, and sometimes it may make sense to do both (track day bro) The amount of oil needed is small, it just needs to be sufficient and consistent, which the factory setup tries to do.
Factor in that too much oil is bad as it lowers knock resistance (octane rating). I will say saw now appreciable difference in performance or general temperatures between just the SOHN and SOHN+premix on short tracks in 100*f weather. I don’t have a way to measure seal surface temp to see if pre-mix served a benefit.
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Scarlet Speedster (01-25-2021)
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Scarlet Speedster (01-25-2021)
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Scarlet Speedster (01-25-2021)
#91
You gonna eat that?
iTrader: (1)
I'm bumping this for recent interest and discussion.
I've been here for about 10 years, I have a new Sohn bundle that I had planned on putting on my 8 in the event of a rebuild.
It only recently occurred to me to check with the person standing behind the warranty of my recently purchased engine, which I've yet to do.
If it will void the warranty, then my interest in it will be gone, and I'll have a kit to sell.
I've seen plenty of points made for the presumed virtues of the Sohn adapter, injecting clean 2 stroke oil designed to burn cleanly and lubricate as opposed to used, possibly contaminated, or 'dirty' conventional motor oil.
I also don't remember seeing any arguments against it other than 'It doesn't help', 'It's not proven', or just plain snarky insults.
References made to some individuals who needed rebuilds alluding to the use of it as a contributing factor are few, I don't know what the long term results have been for proponents who used, or still use them.
Membership attrition isn't helping accumulate much useful evidence either.
If anyone has any solid, logical arguments against using the Sohn adapter other than 'It's not proven' or 'No one can prove it helps', etc., I'd love to hear them, and other members still expressing interest in the kits might as well.
I've been here for about 10 years, I have a new Sohn bundle that I had planned on putting on my 8 in the event of a rebuild.
It only recently occurred to me to check with the person standing behind the warranty of my recently purchased engine, which I've yet to do.
If it will void the warranty, then my interest in it will be gone, and I'll have a kit to sell.
I've seen plenty of points made for the presumed virtues of the Sohn adapter, injecting clean 2 stroke oil designed to burn cleanly and lubricate as opposed to used, possibly contaminated, or 'dirty' conventional motor oil.
I also don't remember seeing any arguments against it other than 'It doesn't help', 'It's not proven', or just plain snarky insults.
References made to some individuals who needed rebuilds alluding to the use of it as a contributing factor are few, I don't know what the long term results have been for proponents who used, or still use them.
Membership attrition isn't helping accumulate much useful evidence either.
If anyone has any solid, logical arguments against using the Sohn adapter other than 'It's not proven' or 'No one can prove it helps', etc., I'd love to hear them, and other members still expressing interest in the kits might as well.
Last edited by BigCajun; 07-23-2022 at 11:32 AM.
#92
Registered
iTrader: (2)
I wonder if there truly is enough pressure differential (vacuum) from the sohn tank compared to the engines oil sump to work well under load. The sohn kit holds what, maybe 2 quarts? The stock stump and oil cooling system holds somewhere around 7 quarts. Being in the hvac world, it is known that pumps create a pressure differential on inlet/outlet of the impeller which is directly affected by the head of water/glycol proceeding, and I am guessing the omp "pump" works the same. While mazda's oil injection rates were pretty low from the factory, I do believe they have designed the system around total capacity in obtaining their figures, or maybe I really have no idea.
To me the 2 stroke oil makes sense, it burns cleaner, leaves less deposits and we all know this, but really how many n/a renesis engines fail because of carbon build in the apex channel or side seal channel? My grandmother driving and shifting at 4k rpm which leads to carbon deposits doesn't count as an example since that is user error in how the engine should be operated. I think a majority of the NA failures in racing are likely due to heat building up on the side seals. I have personally been in 6port FC RX7s with way more miles on their engines compared to the average rx8 engine, and I think this is due to the way the rx8's exhaust ports are designed and how it leads to side seal failure.
I've read a lot about the sohn and it is enticing, but im not convinced it would make a renesis engine last any longer than just running the omp with premix, and possibly doing the omp mod to increase output.
Again, I really have no idea, just adding to the conversation, and basing my assumptions on what past rx7 race cars have been doing. I'm in the camp of if the engine ever does go in mine and the availability and costs of rebuilds is seemingly getting difficult, I would just do the LFX swap and call it a day. I love the chassis and I love the renesis engine, but there is only so much we can do to alleviate its design flaw of the exhaust port design.
Cheers
To me the 2 stroke oil makes sense, it burns cleaner, leaves less deposits and we all know this, but really how many n/a renesis engines fail because of carbon build in the apex channel or side seal channel? My grandmother driving and shifting at 4k rpm which leads to carbon deposits doesn't count as an example since that is user error in how the engine should be operated. I think a majority of the NA failures in racing are likely due to heat building up on the side seals. I have personally been in 6port FC RX7s with way more miles on their engines compared to the average rx8 engine, and I think this is due to the way the rx8's exhaust ports are designed and how it leads to side seal failure.
I've read a lot about the sohn and it is enticing, but im not convinced it would make a renesis engine last any longer than just running the omp with premix, and possibly doing the omp mod to increase output.
Again, I really have no idea, just adding to the conversation, and basing my assumptions on what past rx7 race cars have been doing. I'm in the camp of if the engine ever does go in mine and the availability and costs of rebuilds is seemingly getting difficult, I would just do the LFX swap and call it a day. I love the chassis and I love the renesis engine, but there is only so much we can do to alleviate its design flaw of the exhaust port design.
Cheers
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BigCajun (07-24-2022)
#93
You gonna eat that?
iTrader: (1)
Thanks for the input.
That's some good info.
That's some good info.
#94
Registered
iTrader: (2)
I'm pretty much in the same boat as you BC, my engine has 22k miles so maybe halfway dead (I kid, I kid), and you purchased a crate engine, so ours are pretty close in health I would gather. We both want what's best for it, but I think what's best only goes so far you know? If I drive mine 5k miles a year, I can get potentially 20 years out of the engine, but I'm sure i'll be bored as hell after flying electric cars are blowing by me at 200mph at that point in the future.
#95
You gonna eat that?
iTrader: (1)
I'm pretty much in the same boat as you BC, my engine has 22k miles so maybe halfway dead (I kid, I kid), and you purchased a crate engine, so ours are pretty close in health I would gather. We both want what's best for it, but I think what's best only goes so far you know? If I drive mine 5k miles a year, I can get potentially 20 years out of the engine, but I'm sure i'll be bored as hell after flying electric cars are blowing by me at 200mph at that point in the future.
Driving should be fun.
I recently saw an article about a young woman who bought a 2014 (I think) EV and the battery died shortly after.
The battery was no longer available for it, so she ended up with a very expensive junk car.
#96
You gonna eat that?
iTrader: (1)
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BigCajun (07-24-2022)
#98
I wonder if there truly is enough pressure differential (vacuum) from the sohn tank compared to the engines oil sump to work well under load. The sohn kit holds what, maybe 2 quarts? The stock stump and oil cooling system holds somewhere around 7 quarts. Being in the hvac world, it is known that pumps create a pressure differential on inlet/outlet of the impeller which is directly affected by the head of water/glycol proceeding, and I am guessing the omp "pump" works the same. While mazda's oil injection rates were pretty low from the factory, I do believe they have designed the system around total capacity in obtaining their figures, or maybe I really have no idea.
Cheers
Cheers
I wonder if the Ryan Rotary Performance kit (https://www.ryanrotaryperformance.co...ng-cof-adapter) is actually better than Sohn, since the RRP kit feeds into the top of the OMP vs the Sohn's side?
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BigCajun (07-25-2022)
#99
You gonna eat that?
iTrader: (1)
I have a Sohn on my car and I noticed something the other day, I had the Sohn container about 1/4 full of Amsoil Interceptor oil (yellow in color). When I filled the Sohn with Amsoil Sabre Pro (blue) I could watch Sabre move down to the OMP; it took a few minutes to feed all the way. Sabre is thicker oil than Interceptor and I wonder if it is also a heavier oil, and/or if the added weight from a full Sohn container was pushing down into the OMP better. I just street drive my car but it made me wonder if running a Sohn container that low was causing issues properly feeding the OMP. After a few miles all the OMP lines turned blue with Sabre and I didn't see any air bubbles before or after this observation.
I wonder if the Ryan Rotary Performance kit (https://www.ryanrotaryperformance.co...ng-cof-adapter) is actually better than Sohn, since the RRP kit feeds into the top of the OMP vs the Sohn's side?
I wonder if the Ryan Rotary Performance kit (https://www.ryanrotaryperformance.co...ng-cof-adapter) is actually better than Sohn, since the RRP kit feeds into the top of the OMP vs the Sohn's side?
I only remember one member who had another company's kit but I don't remember who made it.